Re: LW compiler optimizations

Thank you for sharing that. I tried the DOTIMES with a displaced array. And I incorporated your declare types. My timing is still > 15x slower than the vDSP called from Lisp.

Per MAC-pair, my timing shows 6.7 ns/pair, on a 2021 M1 iMac.

Specifically:

(defun fir-dotpr-loop (fir vec &key (start2 0))
  ;; Fastest so far - 335 μs
  #F
  (declare ((simple-array double-float (*)) fir vec)
           (fixnum start2))
  (let* ((sum   0d0)
         (nel   (length fir))
         (v     (make-array nel
                            :element-type 'double-float
                            :displaced-to vec
                            :displaced-index-offset start2)))
    (declare (double-float sum)
             (fixnum nel)
             ((vector double-float *) v)
             (dynamic-extent v))
    (dotimes (ix nel)
      (declare (fixnum ix))
      (setq sum
            (+ sum
               (* (aref fir ix)
                  (aref v ix)))))
    sum))

;; ——————————————

(defparameter *nel*   5633) ;; * 2 arrays, * 4 steps = 45,064 MAC ops/test
(defparameter *tst-fir* (make-array *nel*
                                    :allocation :pinnable
                                    :element-type 'double-float
                                    :initial-contents (map 'vector 'dfloat (vm:unoise *nel*))))
(defparameter *tst-arr* (make-array (+ *nel* 1024)
                                    :allocation :pinnable
                                    :element-type 'double-float
                                    :initial-contents (map 'vector 'dfloat (vm:unoise (+ *nel* 1024)))))

(defun test-lisp-fir-dotpr-loop ()
  ;; 300 μs
  (dotimes (ix 4)
    (declare (fixnum ix))
    (let* ((start (* ix 256)))
      (declare (fixnum start))
      (fir-dotpr-loop *tst-fir* *tst-arr* :start2 start)    ;; simulate real part
      (fir-dotpr-loop *tst-fir* *tst-arr* :start2 start))))

(time
 ;; 300 μs/iter, 37.5 μs/vdot, 6.7 ns/MAC
 ;; alloc 1,050 bytes/iter, 131 bytes/vdot
 (loop repeat 1000 do (test-lisp-fir-dotpr-loop)))


> On Jan 14, 2025, at 10:47, Tim Bradshaw (as tfb at tfeb dot org) <[email protected]> wrote:
> 
> https://github.com/tfeb/bench-df-aref
> 
> I added some more variants since yesterday, and with the best of them LW is not slower than SBCL and neither is slower than C (or than my C): both are about 0.94ns/step on my M1 machine
> 
> --tim
> 
> _______________________________________________
> Lisp Hug - the mailing list for LispWorks users
> [email protected]
> http://www.lispworks.com/support/lisp-hug.html


_______________________________________________
Lisp Hug - the mailing list for LispWorks users
[email protected]
http://www.lispworks.com/support/lisp-hug.html